Treatment of Tobacco Blue-Mold Disease. 3 



handling the formaldehj^de solution should grease their hands with 

 vaseline or use leather gloves that have been greased. 



Seed beds that have been sterilized should not be visited by anyone 

 not directly concerned in their care. Pigs, chickens, and other ani- 

 mals should be rigidly excluded. 



In selecting seed for the coming season the greatest pains should 

 be taken to obtain it from plants not attacked by this disease, and it 

 should be stored so that it can not be contaminated by dust from 

 diseased plants. 



TOBACCO FIELDS. 



Diseased (spotted) leaves should be removed at once as far as 

 practicable and burned. It is probably dangerous to allow these 

 leaves to remain on the land. Xo resting spores have yet been found 

 in the diseased spots, but in fungi of this group thick-walled resting 

 spores are a common way of passing the winter, and they occur al- 

 most certainly in some of the spots on these tobacco leaves. It is the 

 safe thing to assume that the resting spores are present and to gather 

 and destroy the spotted leaves. 



The sound leaves on the plants should be sprayed with fungicides. 

 At present a dilute Bordeaux mixture is probably the safest fungi- 

 cide likely to give results. Experiments are being carried on with 

 various other fungicides. 



If Bordeaux mixture is used it is best made fresh, rather than 

 bought dry, and should not be used stronger than the 2 : 2 : 50 formula, 

 on account of danger of burning the foliage. Great care should be 

 taken to wet the under as well as the upper surface of the leaves, 

 since the fungus penetrates mostly and fruits on the under surface. 

 This treatment should be repeated after rains and generally, rain or 

 shine, as often as every second or third day during the rapidh^ grow- 

 ing period. Nothing can be promised, but we know that such treat- 

 ment has proved successful against the downy mildew of the grape, 

 and it offers the best hope for success of any of the common genni- 

 cidal treatments. 



BORDEAUX MIXTURE. 



To make 2 : 2 : 50 Bordeaux mixture from stock solutions it is only 

 necessary for 2 gallons of the stock solution of copper sulphate 

 (bluestone) to be poured into a suitable container and 2 gallons of 

 the stock solution of the milk of lime into a separate container, dilut- 

 ing each to 25 gallons. The two dilutions are then poured together 

 into the spray tank or into a barrel, from which the tanks are filled. 

 The mixture should be used as soon as made, not allowed to settle. 



To make stock solutions of Bordeaux mixture, proceed as follows : 

 Procure two water-tight barrels and protect from the sun. To pre- 

 vent loss from evaporation each should have also a tight-fitting 



